Resiliently biased starter blade supporting arm for thread roller

ABSTRACT

A thread roller starter mechanism has a starter blade assembly which is paced for operation by a one-way actuating drive which effects retraction of the starter blade assembly from a starting position. The assembly includes a cantilever mounted arm with a starter blade supported on a free end of the blade supporting arm which is resiliently biased to urge the starter assembly to return toward the starting position and to provide a preselected work blank starting force independent of the actuating drive.

United States Patent [191 Morton et a1.

[4 act. 22, 1974 Edward G. Grohoski, Litchfield, both of Conn.

[73] Assignee: The Hartford Special Machinery Company, Simsbury, Conn.

[22] Filed:

Dec. 14, 1973 [21] Appl. No.: 424,664

52 us. Cl. 72/90 [51] Int. Cl B2111 3/06 [58] Field of Search 72/90, 88;10/2, 10; 221/21 [56] References Cited UNITED STATES PATENTS 3,139,7767/1964 Friedman 72/90 3,371.820 3/1968 Grohoski et a1. 72/90 X PrimaryExaminer-Milton S. Mehr Attorney, Agent, or Firm-Prutzman, Hayes, Kalb &Chilton [5 7] ABSTRACT A thread roller starter mechanism has a starterblade assembly which is paced for operation by a one-way actuating drivewhich effects retraction of the starter blade assembly from a startingposition. The assembly includes a cantilever mounted arm with a starterblade supported on a free end of the blade supporting arm which isresiliently biased to urge the starter assembly to return toward thestarting position and to provide a preselected work blank starting forceindependent of the actuating drive.

7 Claims, 2 Drawing Figures RESILIENTLY BIASED STARTER BLADE SUPPORTINGARM FOR THREAD ROLLER This invention generally relates to thread rollersand specifically concerns an improved starter mechanism for suchmachines of a type generally described in our US. Pat. No. 3,371,820entitled Starter Mechanism for Thread Rolling Machine issued Mar. 5,1968 and assigned to the assignee of this invention.

A principal object of this invention is to provide an improved startermechanism having a starter blade assembly the weight and inertia ofwhich is reduced to a minimum for rolling threads on exceptionallylightweight blanks at normal high speed operation.

Another object of this invention is to provide an improved startermechanism of an overload release type wherein the starter blade returnis independent of its drive which is a one-way operating drive forpacing operation of the starter blade.

A further object of this invention is to provide an improved startermechanism wherein the stroke length of the starter blade is adjustablefor blanks of different diameter size without requiring any change inthe feed control contour of a drive actuating cam.

Still another object of this invention is to provide an improved startermechanism which is suited particularly for feeding exceptionallylightweight blanks at a high machine production rate exactly the way itdoes when the machine is being turned over manually during slow speedadjustment to insure that the thread rolling dies of the machine are inmatch.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

A better understanding of the objects, advantages, features, propertiesand relationships of the invention will be obtained from the detaileddescription and accompanying drawings which set forth an illustrativeembodiment and is indicative of a way in which the principle of theinvention is employed.

In the drawings:

FIG. 1 is a partial plan view of a thread rolling machine showing astarter mechanism which is the subject of this invention; and

FIG. 2 is an enlarged side elevational view, partly broken away andpartly in section, showing certain component parts of a starter bladeassembly.

Referring to the drawings in detail, a thread rolling machine isillustrated in FIG. 1. The machine 10 includes an elongated frame ontable 12 on which is mounted a feed chute or guide track 14 forconveying blanks 15 in line from a hopper, not shown, to a pair ofcooperating stationary and reciprocable dies 16 and 18 respectively. Thestationary die 16 is mounted on a stationary die block 20, and thereciprocable die is mounted to a slide 22 by an adjustable clampassembly 24.

Slide 22 is supported for reciprocable movement on a slide block 26which can be adjusted on table 12 by suitable fasteners 28 for insuringalignment of the spacing between the stationary and reciprocable dies 16and 18. A suitable clamp assembly 30 is provided for also making fineadjustment of the stationary die 16 to permit an operator to eliminateundesired clearances. Such adjustment of the stationary die 16 is notnormally provided for, but in this machine it is desirable in an effortto optimize all aspects of blank handling in view of the exceptionallysmall blanks which are being rolled, and if desired, suitable meansincluding fasteners 31 may be provided to effect adjustment ofstationary die 16 parallel to guide track 14.

Guide track 14 will be understood'to be downwardly inclined so thatblanks are fed between rails 34 of track 14. A combination gate andstarter blade 36 is mounted adjacent an open end of track 14 forreciprocable movement between stationary and reciprocable dies 16 and18. Blade 36 is driven for successively feeding each end blank fromtrack 14 to between the starting ends of dies 16, 18. The feeding ofeach blank is initiated and timed to cooperate with reciprocablemovement of slide 22 by a cam 38 attached to and rotating with crankwheel 40.

To reciprocate slide 22 and therefore the driven reciprocable die 18,crank wheel 40 has one end of a pitman arm 42 eccentrically pivotallymounted on a crank wheel 40, and the other end of pitman arm 42 ispivotally connected to slide 22 by pivot pin 44. For each revolution ofcrank wheel 40, reciprocable die 18 is driven through one complete cyclewith the stroke of die 18 being dependent upon the eccentricity of thepivotal mounting of pitman arm 42 to crank wheel 40. To pace operationof starter blade 36, a drive mechanism 46 is provided which serves toretract starter blade 36 in one linear direction to open the end oftrack 14 and to remain open long enough for the single end work blank tobe admitted from track 14 into position between the starting end of eachdie 16, 18. The end blank is to be positioned against the face of themoving die 18 at least by the time the moving die 18 comes to positionat the completion of its backstroke andreverses direction. Then the workblank is wedged between the starting ends of the dies 16, 18 by blade 36to be accurately provided with a thread rolled onto the periphery ofthe-blank upon movement of the reciprocable die 18 relative to the fixeddie 16. The feeding of each blank is timed to cooperate with thereciprocable movement of slide 22.

Drive mechanism 46 includes a bell crank 48 mounted on a pivot pin 50secured to the table 12. Bell crank 48 has an arm 52 suitably connectedby pivot pin 54 to a rod end 56 of turnbuckle 58. Its opposite ends arethreadably connected to rod end 56 and to a similar rod end 60 pivotallyconnected by pin 62 to a cam roll lever 64 pivotally mounted at 66 on astarter engage lever 68 supported for pivotal movement on table 12 on arotary support unit 70. Spring 72 is connected between a post 74 fixedto table 12 and point 75 on arm 76 of the starter engage lever 68 tourge cam roll 78, pivotally supported on lever 64, toward a disengagedposition relative to a feed control contour formed on the outerperiphery of cam 38.

Cam roll 78 may be disengaged from cam 38 under the force of spring 72upon retraction of a positive adjustment stop 80 from its illustratedposition in FIG. 1. Stop 80 is shown having an actuator rod 82 which isconnected to a hand operated knob 84. Knob 84 controls the position ofthe stop 80 and, therefore, the position of pivot point 66 which will beunderstood to be fixed during normal operation to establish the pivotpoint for cam roll lever 64 for an operating cycle of the machine 10with cam roll 78 engaging cam 38.

Cam roll 78 is maintained in constant contact with cam 38 duringoperation by a drive return spring 88 (FIG. 2) housed within drive block90. One end of spring 88 is seated against a spring adjustment plug 92,

received in a threaded end of bore 94 of block 90. An opposite end ofspring 88 surrounds a reduced end portion 95 of a drive plunger 96against which spring 88 seats to urge plunger 96 into engagement withlug 98 of bell crank 48 which is part of the drive mechanism 46.Accordingly, bell crank 48 is urged counterclockwise as viewed in FIG. 1by spring 88 to bias cam roll lever 64 clockwise, via turnbuckle 58, tomaintain cam roll 78 in engagement with cam 38.

A high point or position of maximum radius 100 on the contour of cam 38forces cam roll lever 64 counterclockwise about its pivot point 66 asviewed in FIG. 1 to drive bell crank 48 in one angular direction(clockwise) about its pivot pin 50 against the bias of the drive returnspring 88 to retract blade 36 from its illustrated starting position andopen the discharge end of feed rails 34 of track 14, for discharging anend work blank onto the starting ends of dies 16, 18. Such action isachieved by a starter blade actuating post 104 of bell crank arm 102which is in one-way driving engagement with an L shaped mounting'plate106 for blade 36 to cause blade 36 to be retracted in one direction fromits starting position (from right to left as viewed in FIG. 1) to openthe end of track 14 to permit blank discharge. Subsequent to dischargingthe blank, cam roll 78 passes high point 100 of cam 38 to permit drivereturn spring 88 to move lug 98 of bell crank 48 in a counterclockwisedirection as shown in FIG. 1, thereby returning the starter bladeactuating post 104 to its illustrated start position and permittingreturn of starter blade 36 to its illustrated starting position.

Drive mechanism 46, specifically its bell crank 48 and starter bladeactuating post 104, provides asole connection and drive for starterblade 36. In accordance with this invention, a simple and lightweightstarter blade assembly of improved responsiveness and minimal weight andinertia is provided wherein each end blank is subjected to anexceptionally low starting force limited to only a spring return duringinsertion of the blank between the rolling dies 16, 18 to insure thateach blank is not driven beyond the match point of the dies, i.e., whenthey are matched with the thread crests opposite the thread roots toensure accurate thread tracking without shaving the thread flanks. Aswill be readily recognized by those skilled in the art, exactingrequirements as to the resultant work blank starting force areabsolutely essential to roll threads on exceedingly small blanks, e.g.,small diameter size ranges from approximately 0.045 to 0.125 diameterblanks.

To accomplish the foregoing purposes, a starter blade supporting arm 110is shown as being preferably formed of a flat strip of spring steelcantilever mounted by a suitable fastener 112 on block 90 to extend inoverlying relation to pivot pin 50 of bell crank 48 toward the workstation. A free end of arm 110 is secured to leg 114 of the mountingplate 106 by machine screws 108 with leg 116 projecting perpendicular toleg 114 and serving as a support for blade 36 which is secured theretoby any suitable means. A movable adjustment stop 118 is shown extendingthrough arm 110 and plate 106 with a protruding end portion engageablewith a fixed stop l20on block 90, a lock nut 122 serving to secure stop118 in adjusted position. The disclosed construction serves to provide afine adjustment feature. Normally during set up, the drive mechanism 46is disengaged to shift pivot point 66 to the right of its illustratedposition in FIG. 1, and the starting position of blade 36 is establishedby the stop 118. The turnbuckle 58 is then adjusted to bring post 104into contact with the plate 106 to precisely locate the extreme positionof blade 36 in a blank feeding direction during operation. This featureis also particularly useful in limiting blade position to close the feedtrack 14 when drive mechanism 46 is disengaged.

Arm 110 not only supports blade 36, but the resiliency of the springmaterial itself supplies a propelling force to apply a following motiontostarter blade 36 in a blank feeding direction in response to a returnmovement of bell crank actuating post 104 and a work blank startingforce to wedge each end blank between starting ends of dies 16, 18. Thespring force which the blank is subjected to accordingly may be designedto be exceptionally low, being only enough to cause arm 110, blade 36and its mounting plate 106 and the work blank to follow the returnmotion of post 104 effected by the cam 38 on cam roll lever 64. Anadditional advantage will be seen wherein the exceptionally lightstarting force supplied by arm 110 is insufficient normally to initiatemovement of blade 36 upon occurrence of an abnormal condition as in thecase of a jammed blank obstructing normal feeding of the machine 10,while bell crank 48 will be permitted to continue to oscillateresponsive to the drive mechanism 46.

In the specifically illustrated embodiment, a flat strip of springmaterial is shown at 124 having one end mounted on block by fastener 112in lapping relation to arm and positioned to coextend therewith insupporting relation along a substantial length of arm 110. Spring 124serves to effect a desired additional spring loading to arm 110 upon itsbeing strained when retracted by bell crank 48 while further serving tostabilize arm 110 to minimize undesired oscillation during high speedoperation.

Another feature of the disclosed construction resides in the provisionfor timing control and stroke length adjustment of the end position ofthe retracting extreme limit position of starter blade 36. For thispurpose, an arcuate slot 126 is formed in cam roll lever 64 along an arcequidistant from pivot pin 54 connecting bell crank arm 52 to turnbuckle58. When cam roll 78 is on the low point of the periphery of cam 38 asillustrated in FIG. 1, the starting position of blade 36 as depicted inFIG. 1 will remain constant while the retraction of blade 36 from thestarting position may be adjusted by varying the position of pivot pin62 within its slot 126 between a maximum at one end of the slot 126, asillustrated, and a minimum at the opposite end of the slot. A maximumstroke length may be achieved, e.g., of about three-sixteenths inchtravel, while a minimum stroke length is achieved, e.g., of about threethirtyseconds inch travel for finished diameter screw blanks rangingbetween 0.125 and 0.045 inches at machine production rates of 1,000pieces per minute. Accordingly, the length of starter blade travel canbe tailored by this adjustment to suit the spacing of the guide track 14as required for feeding blanks of varying diameters.

In view of the disclosed construction, the only force exerted on starterblade 36 is that effected by the resil ient biasing force of the starterblade assembly itself which produces a following movement relative tothe actuating post 104 of bell crank 48 in a blank feeding directionupon return movement of the drive mechanism 46. In addition, starterblade stroke length control is effected by the disclosed strokeadjustment means in the cam follower linkage of the drive mechanismwithout any need whatsoever of changing the throw of the drive actuatingcam 38.

As will be apparent to persons skilled in the art, variousmodifications, adaptations and variations of the foregoing specificdisclosure can be made without departing from the teachings of thepresent invention.

We claim:

1. A starter mechanism for high speed gating and feeding of individuallightweight work blanks from a feed chute of a thread rolling machine toa work station between relatively movable thread rolling dies andcomprising a frame, a starter mechanism operatively mounted on the frameand including drive means and a starter assembly, the starter assemblyhaving a movable starter blade for movement in opposite directionstoward and away from a starting position at the work station, the drivemeans including a pivotable crank rotatably supported on the frame andengageable with the starter assembly for pacing movement of its starterblade, the pivotable crank providing a one-way drive to retract thestarter blade away from its starting position upon rotation of the crankin one angular direction, the starter assembly further including astarter blade supporting arm cantilever mounted at one end on the framewith an opposite free end supporting the starter blade for movementtoward and away from its starting position at the work station, the armbeing resiliently biased to urge the starter assembly toward engagementwith the pivotable crank for effecting a following return motion of theblade toward its starting position, upon rotation of the pivotable crankin the opposite angular direction, and for providing a preselectedstarting force on each work blank to wedge it between the thread rollingdies.

2. The starter mechanism of claim 1 wherein the drive means includes adrive actuating cam and cam follower linkage mounted on the frame, thecam follower linkage connecting the cam to the pivotable crank, andadjustment means in the cam follower link- '6 age for varying the extentof retraction of the starter blade from its starting position withoutvarying the throw of the drive actuating cam.

'3. The starter mechanism of claim 1 wherein the bladesupporting arm isformed of a flat strip of spring material, and wherein the resiliency ofthe spring material itself urges the starter blade toward its startingposition and supplies the preselected work blank starting force.

4. The starter mechanism of claim 3 wherein the starter blade is mountedon one surface of the blade supporting. arm, and wherein the starterassembly further includes a spring member engaging a surface of theblade supporting arm opposite its surface on which the starter blade ismounted to provide a desired spring loading, for effecting thepreselected work blank starting force urging the starter blade towardits starting position, upon straining the blade supporting arm whendriven by the pivotable crank in a direction away from the work station.

5. The starter mechanism of claim 4 wherein the spring member is a flatstrip of spring material having one end mounted on the frame in lappingrelation to said one end of the blade supporting arm and disposed incoextensive supporting relation along at least a portion of the lengthof the blade supporting arm.

6. The starter mechanism of claim 3 wherein the starter assembly furtherincludes an L shaped mounting plate having first and second legs insubstantially perpendicular relation to one another, the first leg beingfixed on the free end of the blade supporting arm in generally parallelrelation thereto, the second leg projecting toward the work station, thestarter blade being secured to the second leg of the mounting plate.

engagement therebetween.

1. A starter mechanism for high speed gating and feeding of individuallightweight work blanks from a feed chute of a thread rolling machine toa work station between relatively movable thread rolling dies andcomprising a frame, a starter mechanism operatively mounted on the frameand including drive means and a starter assembly, the starter assemblyhaving a movable starter blade for movement in opposite directionstoward and away from a starting position at the work station, the drivemeans including a pivotable crank rotatably supported on the frame andengageable with the starter assembly for Pacing movement of its starterblade, the pivotable crank providing a one-way drive to retract thestarter blade away from its starting position upon rotation of the crankin one angular direction, the starter assembly further including astarter blade supporting arm cantilever mounted at one end on the framewith an opposite free end supporting the starter blade for movementtoward and away from its starting position at the work station, the armbeing resiliently biased to urge the starter assembly toward engagementwith the pivotable crank for effecting a following return motion of theblade toward its starting position, upon rotation of the pivotable crankin the opposite angular direction, and for providing a preselectedstarting force on each work blank to wedge it between the thread rollingdies.
 2. The starter mechanism of claim 1 wherein the drive meansincludes a drive actuating cam and cam follower linkage mounted on theframe, the cam follower linkage connecting the cam to the pivotablecrank, and adjustment means in the cam follower linkage for varying theextent of retraction of the starter blade from its starting positionwithout varying the throw of the drive actuating cam.
 3. The startermechanism of claim 1 wherein the blade supporting arm is formed of aflat strip of spring material, and wherein the resiliency of the springmaterial itself urges the starter blade toward its starting position andsupplies the preselected work blank starting force.
 4. The startermechanism of claim 3 wherein the starter blade is mounted on one surfaceof the blade supporting arm, and wherein the starter assembly furtherincludes a spring member engaging a surface of the blade supporting armopposite its surface on which the starter blade is mounted to provide adesired spring loading, for effecting the preselected work blankstarting force urging the starter blade toward its starting position,upon straining the blade supporting arm when driven by the pivotablecrank in a direction away from the work station.
 5. The startermechanism of claim 4 wherein the spring member is a flat strip of springmaterial having one end mounted on the frame in lapping relation to saidone end of the blade supporting arm and disposed in coextensivesupporting relation along at least a portion of the length of the bladesupporting arm.
 6. The starter mechanism of claim 3 wherein the starterassembly further includes an ''''L'''' shaped mounting plate havingfirst and second legs in substantially perpendicular relation to oneanother, the first leg being fixed on the free end of the bladesupporting arm in generally parallel relation thereto, the second legprojecting toward the work station, the starter blade being secured tothe second leg of the mounting plate.
 7. The starter mechanism of claim1 wherein the frame provides a fixed stop, wherein the free end of thearm carries a movable stop thereon engageable with the fixed stop, andwherein adjustment means is provided for one of the fixed and movablestops to vary the engagement therebetween.